Tunnel kiln



. H. BETH Feb. 269

TUNNEL KILN Original Filed Dec. 15

INVENTOR fi l/ 70 Maser/z. ,22 BY T 1 1 EY WITNESSES 'Patente Feb. 26, :9

EUGO w. H. Barn, or woncnsrnn, MASSACHUSETTS, assrenon 'ro non'ron comrm, or WORCESTER, MASSACHUSETTS, a oonrona'rron or MASSACHUSETTS.

TUNNEL KILN.

Application filed December 15, 1920, Serial No. 480,876. Renewed January 7, 1924.

To all whom it may cancer n:

Be it known that I, HUGO \V. H. BETH, a citizen of the United States of America, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Tunnel Kilns, of which the following is a full, clear, and exact specification.

My invention relates to tunnel kilns and more particularly to a kiln and kiln car construction providing for a turntable, mounted on the car, which may be rotated during the passage of the car through the tunnel kiln.

In the firing of ceramic ware or other articles which require a high temperature heat treatment, it is important that all parts 01 the article be brought up to the maximum temperature at the same rate. This is difficult to accomplish in tunnel kilns by the use of kiln cars such as those which have been used in the past, due to one or more of various factors which cause an uneven distribution throughout the cross section of the heating chamber.

Likewise if the charge of ware becomes unevenly heated, convection currents of air may be set up through the heating part and not serve to e ualize the temperature throughout. But in either case, the radiated heat from the combustion chamber or what ever may be the source of heat will act only upon that side of the ware whlch 1S nearest to it, and conduction or convection or both together will not entirely make up for the concentration of its heat eiiect upon the ware.

It is accordingly an object of my invention to overcome the dimculties which have been experiencedin the firing of ware which requires a uniform heat treatment and to provide a tunnel kiln construction 1n which this will be accomplished by causing the ware to travel through the kiln upon trucks and rotating the ware during its-passage through the kiln, and to thus improve the quality of the product.

The 1 accompanying drawings illustrate one embodiment of my invention in which:

Figure 1 is a plan view of a kiln car;

Fig. 2 is a longitudinal elevation, partly in cross section, of a kiln car, the tracks and rack bar hereinafter described; and

Fig. 3 is a transverse cross section of a tunnel kiln partly broken away, showing an end elevation of a kiln car in place upon the tracks.

In accordance with my invention, I provide a tunnel kiln construction comprising a car for conveying ceramic or other Ware through the kiln which has a rotatable turntable upon which the ware may be loaded, and I provide suitable mechanism for rotating the turntable while the car is within the kiln.

If it is desired that the turntable be uniformly rotated as it passes through the kiln, it may be operated and controlled by the mechanism ordinarily employed to push suchcars through the kiln, as for example by connecting a gearing on the turntable witllli cooperating partsfixed upon the kiln wa In the embodiment of my invention illustrated in the drawings and which is hereinafter described, I may employ a tunnel kiln 10 provided with parallel longitudinal walls 11 at the sides, and between them a floor 12 whereon are laid the tracks 13. Any method of heating the kiln may be employed, though in the present construction I have shown a kiln of the'Dressler type having the mufiles 14 and heating fines 15.

The kiln car 20, considered as a Whole, is rectangular i'n= shape and. comprises a metallic platform or frame Work 21 suitably mounted on the wheels 22, which in turn rest upon the tracks 13 already mentioned. The turntables 24, the number of which depend upon the size and shape of the car, are circular in cross section and may be built of refractory blocks 25 and 26 of desired shapes which are ,shown as forming a cylindrical space 27 in the center which may be filled with anyrefractory insulatin material such as magnesia; The cylindmcal section formed by the blocks 25 and the superimposed conical section formed by the blocks 26 are held in place, and the blocks in each section are held together, as by a metallic band 28. The top of each turntable 30 may be constructed of a highly refractory material, such as bonded fused alumina, to withstand the temperatures which are to be employed.

In order to rotate this massive body, the upper portion of each of the turntables thus constructed may be fastened to and supported by a metallic plate 33 having an annular ball race 34 which rests upon bearings 35 in a similar ball race 36 which is fastened to the car platform 21. The metallic sup orting plate 33 is fastened to a central shaft 37 which is suitably mounted in bearings in the car platform 21. A bevel gear'38 fixed on the lower end, of shaft 37 meshes with a similar gear 40 on one end of the horizontal shaft 41 which is supported in bearings suspended below the car platform. The shaftv 41 has another bevel gear 42 on its opposite end. The gear 42 of each turntable is so located as to mesh with the single bevel gear 44 which is mounted upon the transverse shaft 45su'pported by a bearing yoke 46, between the forks of which is a gear wheel 47.

The 'rack bar or cog rail 49, which is shown as fastened to the bottom of the kiln, runs throughout the desired portion of the kiln and meshes with the gear wheel 47 on the shaft 45 so that as the car is pushed through the kiln alongthe tracks, as is the customary practice, the wheel 47 is rotated, which, through the gearing already described, causesth turntable to rotate at a speed proportionate to the rate of passage of the car through the kiln. The outer end of the shaft 45 has a squared-off portion 51 to which a crank may be applied for rotat ing the turntables manually.

The rectangular shape of the car is built around the turntables 24, and made level with or slightly lower than the turntable tops, of the special refractory blocks 29, care being taken that they will not interfere with the free passage of the car through the kiln and other moving parts, nor with the rotation of the turntables.

In the operation of my invention, therefore, the ware to be burned is loaded upon the turntables 24 of the kiln car in suitable containers, care being taken that no part of the load projects beyond their circu1nferences and that it be so stacked that there will be no displacement of it during its passage through the kiln. The gear wheel 47 is then rotated by means of a crank applied to the shaft end 51 so that it will properly engage the teeth of the rack bar or cogged rail 49. The ear is then pushed into the kiln, this usually being done automatically and comparatively slowly so that the car and the ware piled upon it will not be unnecessarily disturbed. By this forward movement of the car the gear wheel 47 is made to rotate by its engagement with the stationary rack bar 49 and in turn rotates the shaft 41 which rotates the turntables 24. Accordingly the ware is rotated as it passes along the length of the kiln and uniformly subjected to the heat which is directed upon it by radiation as well as by conduction and convection cur-' rents of the heated air. As a result, all parts of the charge are. uniformly heated, which develops a greater uniformity of structure,

quality and appearance in the product which has been fired in this manner. Consequently, the amount of material which it is necessary to reject is appreciably decreased, thus mak ing a considerable saving in the cost of ultimate manufacture. 7

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A tunnel kiln ,comprising a movable kiln car platform, a refractory turntable mounted thereon to rotate in a horizontal plane, a plane-surfaced layer of super refraetory material on said table to support the ware, a refractory superstructure supported upon said movable platform partially surrounding said turntable at the sides to form a car body having a substantially solid top, and means for rotating the tufntable while the car is within the tunnel ki 11.

2. A tunnel kiln comprising a movable tion of the turntable to provide a car body of -substantially rectangular cross section, and means for rotating the turntable during the passage of the car through the tunnel kiln. v

3. In a tunnel kiln, the combination of parallel longitudinal kiln walls providing a-passage therebetween through the heating chamber of said kiln, and a kiln' car adapted to convey the ware to be fired through said passage, said car having a refractory turntable mounted thereon to rotate in a horizontal plane, and means comprising cooperating members on the car and on a kiln wall for rotating the turntable during the passage of the car through the kiln. v

4. The combination in a tunnel kiln having longitudinal walls, of a kiln ear for conveying the ware to be tired through such a kiln, comprising a movable platform, a refractory turntable for supporting the ware mounted thereon to rotate in a horizontal plane, a refractory superstructure cooperating with said turntable to form a rectangular car body, and means for rotating said turntable during its passage through the kiln comprising gearing connected with the turntable and a member on a kiln wall cooperating with said gearing.

5. The combination in a tunnel kiln having walls and a longitudinal passageway therebetween for a kiln car, of an extensive rack bar fixed on a wall of said kiln and a kiln car for conveying the ware to be fired through said passageway, said car heing provided with a turntable mounted to rotate in a horizontal plane, and means in cluding gears connected with the turntable and engaging said rack bar to rotate the a tnlrntable during its passage through the 6. The combination in a tunnel kiln having a longitudinal wall, of a kiln car for conveying the Ware, comprising a movable 10 platform, turntable plates on said platform,

bearing supports permitting rotation of said plates, refractory superstructures on said plates adapted to support the Ware to be fired, and gear mechanism comprising a rack bar on'a kiln Wall for rotating the turntables simultaneously as the car moves through the kiln.

Signed at Worcester, Massachusetts, this 11th day of Dec., 1920.

HUGO W. H. BETH. 

